The invention is directed to an electrical surge protection device of the type used to protect equipment and electrical circuits from being damaged by overvoltage surges and/or excessive surge currents.
Surge protection devices may be used to protect power lines, communication lines and electrical equipment connected to the power lines and communication lines from overvoltage surges, such as those caused by lightning or power cross conditions, for example. A power cross condition, which may occur as a result of a downed power line, consists of a high voltage and a high current at an alternating frequency, such as 60 Hz.
During an overvoltage surge, a surge protection device may provide temporary surge protection by shunting the overvoltage surge to ground. In the presence of a prolonged overvoltage condition, a surge protection device may also be designed to fail in a short-circuit state. Various embodiments of surge protectors are disclosed in U.S. Pat. No. 5,388,023 to Boy, et al., U.S. Pat. No. 5,500,782 to Oertel, et al., and U.S. Pat. No. 5,880,919 to Napiorkowski, et al.